Bamboo is a prolific woody grass that has long been used in various forms as a construction material. Bamboo possesses numerous properties advantageous to the construction industry. Of particular utility is the high vertical compression strength when used in pole form, also referred to as bamboo cane, as a vertical support member or load bearing element in a structure.
Traditional wood based home building techniques typically include the use of stick lumber, sheeting, panels, beams, trusses, engineered lumber products and other components fashioned from wood in the form of lumber, laminated elements and panels. Consequently the demand for wood is high requiring harvesting rates often exceeding the replenishment rates. Timber bamboo, being a grass, is prolific throughout the world and as a construction material has many advantages over wood including material cost, strength, rapid growth, high carbon sequestration and sustainability making timber bamboo an attractive substitute for wood. Use of timber bamboo as a wood replacement is highly desirable; however, the dimensional format of timber bamboo limits the use as a direct substitute. Consequently the use of bamboo cane, in its natural form as a replacement for traditional wood products, has been limited by inconsistency of cane sizes and structural variations requiring parsing and selection for diameter, length and wall thickness to satisfy structural specifications for each application. Additionally, the inconsistent shapes and dimensions of bamboo cane are difficult and costly to incorporate in the construction of most traditional buildings. Consequently, other methods of using bamboo present in the prior art are principally directed towards utilizing bamboo to replace wood in composite materials such as plywood, panels, or boards wherein the bamboo is shredded, cut into strips, wafers, or chips typically having the size and shape of the equivalent wood material. The portion of the bamboo that most closely mimics the equivalent wood material is the cellulose fibers and vascular components present in the outer portions of the bamboo culm where the density of the fibers and vascular components are high relative to a surrounding lignin natural polymer binder. Typically, the outer third portion of the culm is harvested, discarding the remainder, and shredded or crushed into wafers, chips, strands, flakes or other small shapes that are, in turn, bound together with resins and formed into board such as oriented strand board (OSB). These processes permit manufacturing finished construction materials utilizing bamboo and having consistent and predictable dimensions and structural characteristics. Composite products formed in this matter necessarily break the lignin, the natural bonding material, and then are re-bonded with resin consequently losing a significant portion of the structural characteristics of a bamboo cane. In particular, breaking the natural lignin polymer bonds and re-bonding with resin significantly adds to the weight and cost of the finished material as compared to the weight and cost of the equivalent volume of raw bamboo. Further, and most importantly, the natural high vertical compression strength structure of the bamboo cane is lost.
Regarding panel construction, panel systems typically include vertical stud or post members with sheeting forming the vertical surfaces wherein the sheeting provides a surface and sheer strength. As the sheeting, typically OSB or similar material, has low vertical compression strength, the vertical studs or posts are necessary to provide vertical load bearing. The studs and posts unfortunately provide a thermal bridge between the panel sheets thereby reducing the R value of a panelized wall. Further the studs and posts provide obstructions to the installation of utilities in a panelized wall. What is needed is a high vertical load bearing sheeting element thereby eliminating the need for studs or posts. Wood based sheet products typically are incapable of sustaining the loads. Cane timber bamboo is suitable but dimensionally incompatible.
Utilizing bamboo as a replacement for wood in vertical load bearing construction materials has been problematic. However, bamboo has many advantages over wood as a raw material. Bamboo is generally lower cost than wood. Bamboo is fast growing requiring only 3 to 4 years before harvesting as timber grade bamboo, a growth time significantly less than wood. As compared to wood, bamboo has a higher rot resistance and resistance to insect infestation than most woods in North American climates. Further, bamboo has a higher level of carbon sequestration than most woods. Therefore, what is needed is an improved load bearing construction material principally utilizing bamboo while maintaining the bamboo culm structure largely in tact thereby capitalizing on the advantageous characteristics of timber bamboo while providing a material with substantially consistent and predictable dimensions and structural characteristics such as timber or other load bearing structural components.